Date of Award

January 2026

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Jonathan N. Grauer

Abstract

Background/Scientific Premise: There is growing utilization of surgical intervention for two-level degenerative cervical spine pathology. Multiple treatment options exist. The gold standard remains two-level anterior cervical discectomy and fusion (ACDF), in which the degenerative or herniated cervical discs are removed through an anterior approach to decompress neural elements, followed by fusion of the two involved interspaces to restore stability and alignment. More recently, cervical disc arthroplasty (CDA) has emerged as a viable treatment option for two-level cervical spine pathology, in which the surgeon removes the diseased intervertebral discs and replaces them with artificial discs to reconstruct the segments following decompress neural elements. Alternatively, surgeons and patients may opt for hybrid intervention for two-level pathology, in which one level is treated with ACDF while the adjacent segment is treated with CDA. Each intervention carries unique risks and benefits, ACDF offers reliable neural decompression and immediate segmental stability, with long-term durability and predictable fusion, but at the cost of eliminating motion at the treated level, which may increase adjacent segment stress. In contrast, CDA preserves segmental motion and more physiologic biomechanics, theoretically reducing adjacent segment degeneration, though with concerns regarding implant longevity and more limited long-term outcome data. Research Aims: The goal of the research presented in this thesis was to compare 90-day postoperative adverse events and readmissions, and five-year implant survival to reoperation between two-level ACDF relative to two-level CDA, and two-level ACDF relative to two-level hybrid construct intervention, thus providing a broad overview of postoperative outcomes for alternatives to the current gold-standard (ACDF) for two-level cervical spine interventions. Hypothesis: It was hypothesized that two-level ACDF patients would experience similar rates of 90-day perioperative complications and readmissions but potentially higher long-term revision rates compared to two-level CDA and hybrid constructs. Methods/Approach: Data for the presented retrospective cohort studies were abstracted from the PearlDiver M165 Ortho database. For part 1, patients undergoing two-level ACDF and two-level CDA were isolated. These two cohorts were matched 1:1 based on patient age, sex, and Elixhauser Comorbidity Index (ECI) scores. Odds of 90-day postoperative adverse events were compared between the two groups by multivariable analysis and five-year survival to cervical spine reoperation by log rank test. For part 2, patients undergoing two-level ACDF and two-level hybrid constructs were isolated. Two-level ACDF and two-level hybrid construct patients were matched 1:4 based on age, sex, and ECI scores. Odds of 90-day postoperative adverse events were again compared between the two groups by multivariable analysis and five-year survival to cervical spine reoperation by log rank test. Results: For part 1, compared to 2-level ACDF patients, 2-level CDA patients were younger (average age 49.5 vs 56.8, p<0.0001) and had lower comorbidity burden as measured by the Elixhauser Comorbidity Index (average ECI 3.41 vs 4.04, p<0.0001). After matching 1:1 based on age, sex, and ECI, two cohorts each had 4,224 patients. With controlling for patient age, sex, and ECI on multivariable analysis, two-level CDA patients had significantly lower odds of experiencing 90-day dysphagia (OR 0.60, p<0.0001 driving aggregated any adverse event [OR 0.65, p<0.0001]) and readmission (OR 0.69, p=0.0002). No significant difference in five-year survival to cervical spine reoperation was identified (p=0.7). For part 2, compared to 2-level ACDF patients, hybrid construct patients were younger (average age 49.0 vs 56.8 years, p < 0.0001) and had a lower comorbidity burden (average ECI 3.31 versus 4.04, p < 0.0001). After matching 4:1 based on age, sex, and ECI, there were 5,664 two-level ACDF patients 1,417 two-level hybrid construct patients. With controlling for patient age, sex, and ECI on multivariate analysis, there were no significant differences for postoperative individual adverse events, aggregated any adverse events, readmissions, or five-year survival to reoperation. Scientific Impact: This work represents the largest body of evidence comparing postoperative complications and 5-year implant survival to reoperation between the gold-standard for two-level cervical spine intervention, ACDF, and more novel treatment options including two-level CDA and two-level hybrid constructs. The results of these analyses show two-level ACDF patients to be at higher risk of 90-day complications and readmissions compared to two-level CDA patients, but no difference in 90-day outcomes between two-level ACDF and hybrid constructs. There were no differences in 5-year reoperation rates between two-level ACDF and two-level CDA or hybrid constructs. These findings support a growing body of evidence that CDA or hybrid surgery may be safe and durable alternatives to ACDF for the surgical management of two-level cervical spine degenerative pathology but do not suggest clear superiority of one approach over another.

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